Modern networks can comprise a variety of devices, which may be connected in a variety of ways. A network can be, for example, centralized or ad hoc. In the latter case, each networked device, or node, can act as a router to forward data from other nodes, in addition to communicating its own data.
These wireless networks, however, have their limitations. For example, wireless connections are vulnerable to security breaches, such as replay attacks. Additionally, wireless devices powered by batteries may require frequent battery changes due to the high power cost of wireless data transmission. Because of security and maintenance issues, among other things, ad hoc wireless networks have may not be used in various applications for which the networks might otherwise be suitable.